Sagittarius A* (pronounced "Sagittarius A-star", standard abbreviation Sgr A*) is a bright and very compact astronomical radio source at the center of the Milky Way, near the border of the constellations Sagittarius and Scorpius. It is part of a larger astronomical feature known as Sagittarius A. Sagittarius A* is believed to be the location of a supermassive black hole, like those that are now generally accepted to be at the centers of most spiral and elliptical galaxies. Observations of the star S2 in orbit around Sagittarius A* have been used to show the presence of, and produce data about, the Milky Way's central supermassive black hole, and have led to the conclusion that Sagittarius A* is the site of that black hole.

Sagittarius A or Sgr A is a complex radio source at the center of the Milky Way. It is located in the Sagittarius constellation, and is hidden from view at optical wavelengths by large clouds of cosmic dust in the spiral arms of the Milky Way.